Move internal packages to an internal folder

For reference: https://go.dev/doc/go1.4#internalpackages

internal/cli/scheduler.go

@@ -0,0 +1,47 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package cli // import "miniflux.app/v2/internal/cli"
+
+import (
+	"time"
+
+	"miniflux.app/v2/internal/config"
+	"miniflux.app/v2/internal/logger"
+	"miniflux.app/v2/internal/storage"
+	"miniflux.app/v2/internal/worker"
+)
+
+func runScheduler(store *storage.Storage, pool *worker.Pool) {
+	logger.Info(`Starting background scheduler...`)
+
+	go feedScheduler(
+		store,
+		pool,
+		config.Opts.PollingFrequency(),
+		config.Opts.BatchSize(),
+	)
+
+	go cleanupScheduler(
+		store,
+		config.Opts.CleanupFrequencyHours(),
+	)
+}
+
+func feedScheduler(store *storage.Storage, pool *worker.Pool, frequency, batchSize int) {
+	for range time.Tick(time.Duration(frequency) * time.Minute) {
+		jobs, err := store.NewBatch(batchSize)
+		logger.Info("[Scheduler:Feed] Pushing %d jobs to the queue", len(jobs))
+		if err != nil {
+			logger.Error("[Scheduler:Feed] %v", err)
+		} else {
+			pool.Push(jobs)
+		}
+	}
+}
+
+func cleanupScheduler(store *storage.Storage, frequency int) {
+	for range time.Tick(time.Duration(frequency) * time.Hour) {
+		runCleanupTasks(store)
+	}
+}